Attention is directed to commonly owned patents and copending applications:
U.S. Pat. No. 6,214,513, discloses a coating process for the fabrication of organic photoreceptors which process employs an electrically conductive single slot die biased to allow an electric field between the die and the ground plane on the photoreceptor substrate. The homogenous coating dispersion is fed through the die at a predetermined gap and rate to control coating thickness at the same time that an electric field is applied. The formulation, rheology, particle mobility, coating speed, electric field and the like are controlled so that the photogenerator particles migrate to the substrate in the dwell time defined by the coating die region.
U.S. Ser. No. 09/716,412, filed Nov. 21, 2000, discloses a coating apparatus which includes a coating device that dispenses coating material, a rotation device that rotates an object to be coated, and a movement device that effects relative movement of the coating device and the rotation device in a direction parallel to a rotation axis of the rotation device. The coating device in a specific embodiment includes a slot, extending substantially parallel to the rotation axis of the rotation device, through which the coating material is dispensed. A relationship of (a) a ratio R of an angular speed of rotation of the rotation device to a speed of the relative movement and (b) a length L of the slot is R=2xcfx80/L.
The disclosures of each of the above mentioned patent and copending applications are incorporated herein by reference in their entirety. The appropriate components and processes of these patents may be selected for the toners and processes of the present invention in embodiments thereof.
The present invention is generally directed to an apparatus and processes for treating, such as by coating substrates, and more specifically, to a coating apparatus including a coating die with one or more laser position sensors and which coating die enables coating processes that deliver precise coating layer thicknesses and widths to, for example, cylindrical, sheet, or web substrates. The resulting precision coated substrates provide articles or devices that are useful in, for example, printing systems and printing processes such as organic film coated drum photoconductors, thermal fusing rolls, and the like useful articles. The apparatus and coating processes of the present invention can be adapted to provide value-added and enhanced performance capabilities to known printing and copying devices, such as printers, copiers, facsimile, and related multifunction printing devices.
In embodiments of the present invention can be readily adaptable to the manufacture of precision coated articles, such as, photoreceptor rolls and drums, fuser rolls, backer rolls, cleaning rolls, specialty coated papers or transparency stock, photoreceptor web stock, coated paper web stock, and the like articles or materials.
In embodiments, the coating processes of the present invention provide valuable benefits and excellent satisfaction levels in the manufacturer of coated articles and apparatus or devices incorporating the coated articles, for example, in providing coater articles with uniform coating thicknesses and homogenous coating layers, in avoiding materials waste or reducing manufacturing cycle times and costs, and in downtime and productivity losses associated less efficient coating methods and apparatuses. These and other advantages of the present invention are achievable.
There remains a need for reducing defects resembling brush marks along each edge of the deposited coating. These brush marks can remain as defects in the dried coating and can ultimately print out as undesirable artifacts in the final electrophotographic copy.
In a typical electrostatographic printing system, a light image or digital image of an original to be reproduced is recorded in the form of an electrostatic latent image upon a photosensitive member such as an organic photoconductor and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles which are commonly referred to as toner. The visible toner image is then in a loose powdered form and can be easily disturbed or destroyed. The toner image is usually fixed or fused, for example with a thermal or radiant fuser roll, upon a support which may be the photosensitive member itself or another support sheet such as plain paper. Other related marking technologies are known, for example, liquid immersion development, and solid or liquid ink jet imaging technologies wherein a liquid, solid, molten, sublimed, and the like marking formulations are deposited onto an imaging member, imaging intermediate member, or image receiver.
In the dip coating process, a cylindrical drum is dipped into a tank of coating material and then withdrawn, with a portion of the coating material adhering to the drum. The adhered coating material is then allowed to cure.
In the slot die coating process, coating material is caused to flow through a slot while a photoreceptor belt of a width approximately equal to the length of the slot is fed past the slot in a direction transverse to the length of the slot.
It is difficult to slot coat a high quality single layer coating of a charge generation layer onto a substrate primarily because of generally low liquid viscosity of the coating, shear thinning and yielding stress due to the nature of the dispersion and the typically extremely thin layer requirements. For example, the benzimidazole perylene (BzPe) and Hydroxygallium phthalocyanine (HOGaPc) solutions that are used to produce photoreceptors have very narrow coating windows. Thus, a need exists for improved coating methods that provide higher yield and higher quality of coated substrates.
In U.S. Pat. No. 6,106,671, issued Aug. 22, 2000, to Heaven, et al., there is disclosed an apparatus and method for controlling the size of a gap through which material is metered. The gap is defined by a rigid surface and a flexible surface connected to at least one actuator for deforming the flexible surface. A plurality of sensors are positioned along the rigid or flexible surfaces to detect the other of the surfaces and generate signals indicating its position. A computing unit in communication with the plurality of sensors processes the signals to generate a continuous gap measurement profile. The computing system also stores a predetermined desired gap measurement profile. A control system in communication with the computing unit actuates the actuators to deform the flexible surface to adjust the gap measurement profile to correct any deviation from the desired gap measurement profile.
In U.S. Pat. No. 5,358,673, issued Oct. 25, 1994, to Heller, et al., there is disclosed a solid three-dimensional article formed from a liquid medium by initially coating a layer of the liquid medium on a fixedly mounted apertured support plate. An initial cross-section or profile of the article then is formed by solidifying the liquid medium, or at least a portion thereof, on the support plate. In another embodiment, each layer of the liquid medium is formed by dispensing the entire layer from above the fixed support plate. In a further embodiment, a device is disclosed for dispensing a liquid medium in layers of uniform thickness on the medium surface of a laser modeling machine, for solidification when subjected to prescribed energy. The dispenser contains an elongated applicator or coating bar of rectangular, essentially solid construction, with a liquid medium reservoir and dispensing passageways located adjacent a dispensing side of the bar. A feed tube and traversing mechanism support rods are secured to an opposite side of the bar. The dispensing passageways may be apertures arranged in multiple rows, with the apertures in at least one row offset with respect to the apertures in the other rows, for more uniform dispensing. In the alternative, the passageways may be inclined slots having portions overlapping in a direction extending longitudinally of the bar.
In U.S. Pat. No. 6,214,513, issued Apr. 10, 2001, to Xerox Corporation, there is disclosed a coating process for the fabrication of organic photoreceptors employs an electrically conductive single slot die biased to allow an electric field between the die and the ground plane on the photoreceptor substrate. The homogenous coating dispersion is fed through the die at a predetermined gap and rate to control coating thickness at the same time that an electric field is applied. The formulation, rheology, particle mobility, coating speed, electric field and the like are controlled so that the photogenerator particles migrate to the substrate in the dwell time defined by the coating die region
The aforementioned references are incorporated in their entirety by reference herein.
This invention and embodiments provide coating methods and apparatuses that overcome or minimize the disadvantages of dip coating and employ some of the advantages of slot die coating.
This invention and embodiments provide methods and apparatuses for coating objects without dip coating. The methods and apparatuses offer uniform, fast coating by dispensing coating material onto a rotated object in a helical pattern. In one aspect of the invention, a coating apparatus includes a coating device that dispenses coating material, a rotation device that rotates an object to be coated, and a movement device that relatively moves the coating device and the rotation device in a direction parallel to a rotation axis of the rotation device. The coating device in a specific embodiment includes a slot, extending substantially parallel to the rotation axis of the rotation device, through which the coating material is dispensed. Aspects of the present invention include the following:
A process comprising:
providing a moving substrate;
applying at least one coating layer onto the moving substrate wherein the at least one coating is a photoconductive material, an electrically insulating material, a hole transport material, an anti-curl material, or an adhesive material, with a slot die coater equipped with at least one position sensor mounted on at least one end of the slot die coater, and applying, for example, from one to about five coating layers on the substrate;
sensing the position of the slot die coater relative to the moving substrate with at least one position sensor; and
when the position of the slot die coater relative to the moving substrate deviates from a set of predetermined coordinates,
iteratively adjusting the position of the die coater relative to the surface of the substrate to return to the set of predetermined coordinates.
An apparatus comprising:
a movement device that moves an object to be coated;
a slot die coater equipped with a position sensor mounted on at least one end of the slot die coater and which slot die coater controllably dispenses coating material onto the moving object; and
at least one servor motor-controller system in electrical contact with the position sensor,
wherein the position sensor senses the position of the slot die coater relative to the object and wherein the at least one servor motor-controller system adjusts the position of the slot die coater relative to the object if the position of the slot die coater relative to the moving substrate deviates from a set of predetermined coordinates.
This invention also provides systems and methods for coating a moving substrate using a slot die.
In various exemplary embodiments of the systems and methods of this invention, a charge generator layer dispersion is fed from a coating die containing a single slot onto a moving substrate. An electrical field is imposed between the coating die and the moving substrate. The dispersion particles that form the charge generation layer are changed. Thus, under the electrical field, these particles deposit on the substrate while still in the coating gap region.
A charge generating layer can be xe2x80x9cdevelopedxe2x80x9d out using the single slot die to provide a charger generating layer (CGL) or both a (CGL) and a charge transport layer CTL simultaneously with the single slot. Thus, a two layer coating can be produced using only a single slot die and a single coating solution. This eliminates one entire coating sequence while improving both productivity and yield.
This invention can be used to produce electrostatographic charge generating material with an increased yield, better layer properties, thinner layers and increased throughput.
Embodiments of the present invention, include:
A process comprising:
providing a moving substrate for coating;
applying at least one coating layer onto the moving substrate with a slot die coater equipped with at least one position sensor mounted on at least one and for example from one to about five end of the slot die coater;
sensing the position of the slot die coater relative to the moving substrate with the at least one position sensor; and
if the position of the slot die coater relative to the moving substrate deviates from a set of predetermined coordinates, then
iteratively adjusting the position of the die coater relative to the surface of the substrate to return to the set of predetermined coordinates; and
an apparatus comprising:
a movement device that moves an object to be coated;
a slot die coater equipped with a position sensor mounted on at least one end of the slot die coater and which slot die coater controllably dispenses coating material onto the moving object; and
at least one servor motor-controller system in electrical contact with the position sensor,
wherein the position sensor senses the position of the slot die coater relative to the object and wherein the at least one servor motor-controller system adjusts the position of the slot die coater relative to the object if the position of the slot die coater relative to the moving substrate deviates from a set of predetermined coordinates.
These and other embodiments of the present invention are illustrated herein.